Added codec: hexagram

dhondta · dhondta · commit c0cd162f0e62 · 2022-02-03T23:29:52.000+01:00
diff --git a/README.md b/README.md
@@ -213,10 +213,11 @@ o
 
 #### BaseXX
 
-- [X] `ascii85`: classical ASCII85 (Python3 only)
-- [X] `baseN`: see [base encodings](https://python-codext.readthedocs.io/en/latest/enc/base.html) (incl base32, 36, 45, 58, 62, 63, 64, 91, 100, 122)
+- [X] `baseN`: see [base encodings](https://python-codext.readthedocs.io/en/latest/enc/base.html) (incl [z]base32, 36, 45, 58, 62, 63, 64, [z]85, 91, 100, 122)
 - [X] `base-genericN`: see [base encodings](https://python-codext.readthedocs.io/en/latest/enc/base.html) ; supports any possible base
 
+This category also contains `ascii85`, `adobe`, `[x]btoa`, `zeromq` with the `base85` codec.
+
 #### Binary
 
 - [X] `baudot`: supports CCITT-1, CCITT-2, EU/FR, ITA1, ITA2, MTK-2 (Python3 only), UK, ...
@@ -302,6 +303,7 @@ o
 
 #### Steganography
 
+- [X] `hexagram`: uses Base64 and encodes the result to a charset of [I Ching hexagrams](https://en.wikipedia.org/wiki/Hexagram_%28I_Ching%29) (as implemented [here](https://github.com/qntm/hexagram-encode))
 - [X] `klopf`: aka Klopf code ; Polybius square with trivial alphabetical distribution
 - [X] `resistor`: aka resistor color codes
 - [X] `rick`: aka Rick cipher (in reference to Rick Astley's song "*Never gonna give you up*")
diff --git a/codext/stegano/__init__.py b/codext/stegano/__init__.py
@@ -1,4 +1,5 @@
 # -*- coding: UTF-8 -*-
+from .hexagram import *
 from .klopf import *
 from .resistor import *
 from .rick import *
diff --git a/codext/stegano/hexagram.py b/codext/stegano/hexagram.py
@@ -0,0 +1,37 @@
+# -*- coding: UTF-8 -*-
+"""Hexagram Codec - hexagram content encoding.
+
+This codec:
+- en/decodes strings from str to str
+- en/decodes strings from bytes to bytes
+- decodes file content to str (read)
+- encodes file content from str to bytes (write)
+"""
+from ..__common__ import *
+
+
+if PY3:
+    __examples__ = {
+        'enc(hexagram|iching|i-ching-hexagrams)': {'this is a test': "䷰䷭䷚䷔䷞䷺䷗䷔䷞䷺䷗䷚䷏䷊䷂䷕䷞䷈䷇☯"},
+    }
+
+    ENCMAP = {c1: c2 for c1, c2 in zip("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
+                                       "䷁䷗䷆䷒䷎䷣䷭䷊䷏䷲䷧䷵䷽䷶䷟䷡䷇䷂䷜䷻䷦䷾䷯䷄䷬䷐䷮䷹䷞䷰䷛䷪䷖䷚䷃䷨䷳䷕"
+                                       "䷑䷙䷢䷔䷿䷥䷷䷝䷱䷍䷓䷩䷺䷼䷴䷤䷸䷈䷋䷘䷅䷉䷠䷌䷫䷀☯")}
+    DECMAP = {c2: c1 for c1, c2 in ENCMAP.items()}
+    
+    def hexagram_encode(input, errors="strict"):
+        return "".join(ENCMAP[c] for c in codecs.encode(input, "base64")), len(input)
+    
+    def hexagram_decode(input, errors="strict"):
+        r, ehandler = "", handle_error("hexagram", errors, decode=True)
+        for i, c in enumerate(input):
+            try:
+                r += DECMAP[c]
+            except KeyError:
+                r += ehandler(c, i, r)
+        return codecs.decode(r, "base64"), len(input)
+
+    add("hexagram", hexagram_encode, hexagram_decode, printables_rate=0.,
+        pattern=r"^(?:(?:i-ching-)?hexagrams?|i-?ching)$")
+
diff --git a/docs/enc/stegano.md b/docs/enc/stegano.md
@@ -4,6 +4,23 @@
 
 -----
 
+### Hexagrams (I Ching)
+
+This uses Base64 and then encodes output characters to [I Ching Hexagrams](https://en.wikipedia.org/wiki/Hexagram_%28I_Ching%29) such that implemented [here](https://github.com/qntm/hexagram-encode).
+
+**Codec** | **Conversions** | **Aliases** | **Comment**
+:---: | :---: | --- | ---
+`hexagram` | text <-> hexagrams-encoded Base64 | `hexagrams`, `i-ching-hexagrams`, `iching` | Python3 only
+
+```python
+>>> codext.encode("this is a test", "hexagram")
+'䷰䷭䷚䷔䷞䷺䷗䷔䷞䷺䷗䷚䷏䷊䷂䷕䷞䷈䷇☯'
+>>> codext.decode("䷰䷭䷚䷔䷞䷺䷗䷔䷞䷺䷗䷚䷏䷊䷂䷕䷞䷈䷇☯", "iching")
+'this is a test'
+```
+
+-----
+
 ### Klopf Code
 
 This is a Polybius code with the trivial alphabetical distribution ("A" -> (1,1), "B" -> (2,1), ...). This can be tested [here](https://gc.de/gc/klopfcode/).

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,5 @@`
`1`	`1`	`# -- coding: UTF-8 --`
	`2`	`+from .hexagram import *`
`2`	`3`	`from .klopf import *`
`3`	`4`	`from .resistor import *`
`4`	`5`	`from .rick import *`